package leetcode;

import java.util.HashMap;
import java.util.Map;

/**
 * Created by lyk on 2017/4/17.
 * Package name: leetcode
 * Porject name: untitled1
 */
public class ImplementTrie {
    public static void main(String[] args) {
        ImplementTrie it = new ImplementTrie();
        it.insert("abc");
        it.insert("bull");
        it.insert("buy");
        it.insert("bid");
        it.insert("ab");
        System.out.println(it.search("abc"));
        System.out.println(it.startsWith("a"));
        System.out.println(it.search("bi"));
    }
    private TrieNode root;

    public ImplementTrie() {
        root = new TrieNode();
    }

    // Inserts a word into the trie.
    public void insert(String word) {
        HashMap<Character, TrieNode> children = root.children;

        for(int i=0; i<word.length(); i++){
            char c = word.charAt(i);

            TrieNode t;
            if(children.containsKey(c)){
                t = children.get(c);
            }else{
                t = new TrieNode(c);
                children.put(c, t);
            }

            children = t.children;

            //set leaf node
            if(i==word.length()-1)
                t.isLeaf = true;
        }
    }

    // Returns if the word is in the trie.
    public boolean search(String word) {
        TrieNode t = searchNode(word);

        if(t != null && t.isLeaf)
            return true;
        else
            return false;
    }

    // Returns if there is any word in the trie
    // that starts with the given prefix.
    public boolean startsWith(String prefix) {
        if(searchNode(prefix) == null)
            return false;
        else
            return true;
    }

    public TrieNode searchNode(String str){
        Map<Character, TrieNode> children = root.children;
        TrieNode t = null;
        for(int i=0; i<str.length(); i++){
            char c = str.charAt(i);
            if(children.containsKey(c)){
                t = children.get(c);
                children = t.children;
            }else{
                return null;
            }
        }

        return t;
    }
}
class TrieNode {
    char c;
    HashMap<Character, TrieNode> children = new HashMap<Character, TrieNode>();
    boolean isLeaf;

    public TrieNode() {}

    public TrieNode(char c){
        this.c = c;
    }
}